Are There Evil Spirits?

Many people who are not regular church-goers will say they are "spiritual, but not religious."  What does this mean?  Unfortunately, the term "spiritual" is not universally defined.  However, many who do use the term talk about good spirits (Angels?) and bad spirits (Demons?), the same way religious people do.

Most atheists I know, including me, totally reject the concept of the spiritual, as modern physics has shown that there is no room for any supernatural entities in our classical, Newtonian reality (see a previous post discussing this).  Given this situation with most atheists, and many fundamentalist religious folks thinking us atheists are evil or possessed by evil spirits,  why has there not been a documented case of an atheist showing the "signs" of being possessed and then being exorcised of his or her evil spirits?  In other words, why is it only "believers" who respond to the rites of exorcism?